随着基于生物学的疗法扩展，LC-MS越来越多地应用于支持定量生物分析以检测不同的肽和蛋白质。与配体结合测定（LBA）的传统方法相比，LC-MS可以提供一些显着的优点，但通常被认为是互补方法。
Aaron Ledvina，博士学位的方法开发和Brendan Powers，博士，职员科学家，最近分享了对LC-MS和LBA战略的思考，以获得生物量化。
了解监管验收
“Over the last five to ten years, the LC-MS platform has become increasing routine and accepted, both scientifically and from a regulatory standpoint,” said Ledvina.
虽然FDA鼓励使用替代技术，但在确定是否使用LC-MS或LBA时，存在许多因素。
“You start with the biological information that you need to access and determine the specific measurements needed; this, in combination with understanding the nature of the measurement associated with LC-MS or LBA, often make the choice of platform more obvious,” he explained. “At a high level, sample cost is usually lower for LBAs but the development time tends to be faster for LC-MS, especially for certain classes of compounds such as monoclonal antibodies in preclinical studies.”
评估互补的方法
“LC-MS and LBA can be thought of as complimentary to one another, but the choice of platform depends on a number of different variables.” said Powers. “One of the most important factors is the availability of critical reagents.”
LBA的一个缺点是对高质量的关键试剂的要求，这需要仔细的文档和标记，以最小化在冗长的生产过程中从批量批次中的可变性。在早期发现生物分析中，LC-MS没有面对通常容易获得的通用试剂相同的担忧。
The importance of sensitivity
Sensitivity represents another important consideration. “For toxicology studies, the lower limit of quantitation (LLOQ) is usually much higher, making LC-MS more practical,” explained Powers. “But for pharmacokinetic (PK) studies, higher sensitivity is typically required due to lower doses. For example, the LLOQ is 20 ng/mL for our LBA PK assay, but our direct digest LC-MS assay can only get down to 500 ng/mL.”
In one case study with antidrug antibodies (ADA), LBA offered superior LLOQ, throughput and extraction time; whereas LC-MS (Direct Digest) offered superior precision and accuracy. When antidrug antibodies (ADA) were included, increasing ADA proportionally reduced the LBA signal, while LC-MS was not affected.
启用多路复用
LC-MS为多路复用抗体定量提供LBA的优势。“在常规给药中，您一次评估一抗抗体或药物，然后进行分析，”解释为“。“但由于增强的选择性LC-MS提供了，您可以同时给药多种抗体，并在同一运行中进行分析，而无需高质量的临界试剂。”
Differing enrichment approaches
其他考虑因素包括不同的替代肽方法。“在最近的一个案例研究中，我们使用蛋白G，其富集抗体，”的力量。“蛋白质G的富集在消化抗体药物之前提供通用样品清洁。由于后端的LC-MS给了我们所需的选择性，因此不需要有针对性的浓缩。即使样品仍然相当复杂，我们也能够减轻干扰峰，并通过替代（签名）肽选择性定量靶抗体。“
Increasing sensitivity and looking ahead
In the past, there was a long held trend of only using LBA, but now the Covance is team increasingly asked to support pharmaceutical companies with LC-MS to evaluate their complex molecules with custom approaches.
“Our team is working to meet the needs of our clients by developing high resolution MS methods for intact protein analysis and optimizing custom immunoaffinity and digestion workflows,” said Ledvina.
“对于LC-MS，我们也在添加微射线能力的过程中，这可以提供整体敏感性的良好凹凸。这只是我们希望改善对LBA更具竞争力的方法，并为客户提供更多选择的方法。“
Whether using LBA or LC-MS or both, learn more about your choices for biologic quantification at Covance:Covance.com/BioA
